Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 341: What is true about the synovial membrane of the knee joint?

A. It is invaginated posteriorly by the cruciate ligament. (Correct Answer)
B. It extends into the prepatellar bursa.
C. It covers the inferior surface of both menisci.
D. It extends into the infrapatellar bursa.

Explanation: ### Explanation **Correct Option: A. It is invaginated posteriorly by the cruciate ligament.** The knee joint is unique because the **cruciate ligaments (ACL and PCL)** are **intracapsular but extrasynovial**. During development, the synovial membrane is invaginated from the posterior aspect of the joint. It reflects forward around the ligaments, covering them anteriorly and on their sides. Consequently, the cruciate ligaments are excluded from the synovial cavity, even though they lie within the fibrous capsule. **Why the other options are incorrect:** * **Option B (Prepatellar bursa):** The prepatellar bursa lies subcutaneously, anterior to the patella. It does **not** communicate with the knee joint cavity. * **Option C (Menisci):** The synovial membrane lines the fibrous capsule but **does not cover the superior or inferior surfaces of the menisci**. The menisci are intra-articular structures bathed in synovial fluid; covering them with a membrane would interfere with their weight-bearing and lubricating functions. * **Option D (Infrapatellar bursa):** There are two infrapatellar bursae: the superficial (subcutaneous) and the deep. Neither communicates with the synovial cavity of the knee. Note that the **suprapatellar bursa** is the one that always communicates with the joint cavity. **High-Yield Facts for NEET-PG:** * **Suprapatellar Bursa:** This is the largest bursa and is an extension of the synovial cavity. It is held in place by the **Articularis Genu** muscle. * **Infrapatellar Fold:** The synovial membrane forms a fold anteriorly called the infrapatellar synovial fold, which contains the **infrapatellar fat pad (Hoffa’s fat pad)**. * **Popliteus Tendon:** This is also **intracapsular but extrasynovial** at its origin, similar to the cruciate ligaments. * **Baker’s Cyst:** A herniation of the synovial membrane, usually into the semimembranosus bursa posteriorly.

Question 342: The medial meniscus of the knee joint is injured more often than the lateral meniscus because the medial meniscus is relatively:

A. More mobile
B. Less mobile (Correct Answer)
C. Thinner
D. Attached lightly to the femur

Explanation: The medial meniscus is injured approximately 20 times more frequently than the lateral meniscus. This is primarily due to its fixity and lack of mobility. Why "Less Mobile" is Correct: The medial meniscus is C-shaped and firmly attached to the deep surface of the Medial Collateral Ligament (MCL). This anatomical tethering restricts its movement during knee rotation and extension. When a forceful twisting injury occurs, the medial meniscus cannot glide out of the way of the femoral condyles, leading to entrapment and tearing. In contrast, the lateral meniscus is nearly circular, smaller, and not attached to the Fibular Collateral Ligament; it is also separated from the capsule by the popliteus tendon, making it significantly more mobile and "evasive" during trauma. Analysis of Incorrect Options: * A. More mobile: Increased mobility is a protective factor (seen in the lateral meniscus). * C. Thinner: While the medial meniscus is narrower anteriorly, its thickness is not the primary reason for injury; its lack of displacement is. * D. Attached lightly to the femur: Menisci are attached to the tibia (via coronary ligaments), not the femur. High-Yield NEET-PG Pearls: 1. O’Donoghue’s Unhappy Triad: A classic injury involving the Medial Meniscus, Medial Collateral Ligament (MCL), and Anterior Cruciate Ligament (ACL). 2. Shape: Medial = 'C' shaped (larger radius); Lateral = 'O' shaped (smaller radius). 3. Blood Supply: Only the peripheral 1/3 (Red Zone) is vascularized and has healing potential; the inner 2/3 (White Zone) is avascular. 4. McMurray Test: Used clinically to diagnose meniscal tears (Internal rotation for lateral meniscus; External rotation for medial meniscus).

Question 343: The common peroneal nerve is related to which of the following structures?

A. Shaft of tibia
B. Neck of fibula (Correct Answer)
C. Lower tibio-fibular joint
D. Shaft of fibula

Explanation: ### Explanation **Correct Answer: B. Neck of fibula** The **Common Peroneal Nerve (CPN)**, also known as the common fibular nerve, is a terminal branch of the sciatic nerve. It descends through the popliteal fossa and winds laterally around the **neck of the fibula**. At this specific anatomical landmark, the nerve lies subcutaneously, resting directly against the bone before dividing into its superficial and deep peroneal branches within the fibularis longus muscle. **Analysis of Incorrect Options:** * **A & D (Shaft of Tibia/Fibula):** The CPN does not travel along the mid-shaft of either bone. The tibial nerve is related to the posterior aspect of the tibia, while the peroneal nerve branches are deep to the muscles along the fibular shaft. * **C (Lower tibio-fibular joint):** This joint is located at the ankle. By this level, the CPN has already bifurcated into the deep peroneal nerve (which enters the foot) and the superficial peroneal nerve. **Clinical Pearls & High-Yield Facts for NEET-PG:** * **Most Common Site of Injury:** The neck of the fibula is the most common site for CPN compression or injury due to its superficial location. * **Clinical Presentation:** Injury at this site leads to **Foot Drop** (loss of dorsiflexion) and **Equinovarus** deformity, along with sensory loss on the dorsum of the foot. * **Causes of Injury:** Tight plaster casts, leg crossing, or fractures of the fibular neck. * **Mnemonic:** **PED** (Peroneal Everts and Dorsiflexes; if injured, you get **Drop** foot).

Question 344: Which muscle originates from the anterior superior iliac spine of the hip bone?

A. Iliacus
B. Sartorius (Correct Answer)
C. Vastus Medialis
D. Pectineus

Explanation: The **Sartorius** muscle is the correct answer as it originates from the **Anterior Superior Iliac Spine (ASIS)** of the hip bone. It is the longest muscle in the human body and belongs to the anterior compartment of the thigh. It follows an oblique course across the thigh to insert into the upper part of the medial surface of the tibia (forming part of the *Pes Anserinus*). **Analysis of Options:** * **Iliacus:** Originates from the **Iliac fossa** (upper two-thirds) and the inner lip of the iliac crest. It joins the psoas major to insert into the lesser trochanter of the femur. * **Vastus Medialis:** This is part of the Quadriceps femoris. It originates from the **intertrochanteric line** and the medial lip of the **linea aspera** on the femur, not the hip bone. * **Pectineus:** Originates from the **pectineal line (pecten pubis)** on the superior ramus of the pubis. **High-Yield Clinical Pearls for NEET-PG:** 1. **ASIS Landmarks:** Two structures attach to the ASIS: the **Sartorius** muscle and the lateral end of the **Inguinal Ligament**. 2. **Tailor’s Muscle:** Sartorius is known as the "Tailor's muscle" because its actions (flexion, abduction, and lateral rotation of the hip; flexion of the knee) produce the cross-legged sitting posture. 3. **Pes Anserinus:** Remember the mnemonic **"SGT"** for the three muscles inserting at the medial tibia: **S**artorius, **G**racilis, and semi**T**endinosus. 4. **Nerve Supply:** Sartorius is supplied by the **Femoral Nerve (L2, L3)**.

Question 345: A 7-year-old girl sustains an injury to a nerve that passes superior to the piriformis muscle and winds around the greater sciatic notch. Which of the following muscles is most likely affected?

A. Gluteus medius (Correct Answer)
B. Gluteus maximus
C. Obturator internus
D. Piriformis

Explanation: ### Explanation The correct answer is **Gluteus medius**. **1. Why Gluteus medius is correct:** The nerve described is the **superior gluteal nerve (L4–S1)**. Anatomically, this nerve exits the pelvis through the **greater sciatic foramen**, specifically passing **superior to the piriformis muscle**. After exiting, it runs between the gluteus medius and gluteus minimus muscles. It supplies three specific muscles: the **gluteus medius**, **gluteus minimus**, and **tensor fasciae latae (TFL)**. Therefore, an injury to this nerve directly affects the gluteus medius. **2. Why the other options are incorrect:** * **Gluteus maximus:** This muscle is supplied by the **inferior gluteal nerve**, which exits the greater sciatic notch **inferior** to the piriformis muscle. * **Obturator internus:** This muscle is supplied by the nerve to obturator internus (L5–S2), which also passes **inferior** to the piriformis. * **Piriformis:** This muscle is supplied by direct branches from the sacral plexus (**S1, S2 nerve roots**) before they exit the foramen. The superior gluteal nerve passes over it but does not supply it. **3. NEET-PG Clinical Pearls:** * **Trendelenburg Sign:** Injury to the superior gluteal nerve leads to paralysis of the gluteus medius and minimus. This results in the "dropping" of the pelvis on the unaffected side when the patient stands on the affected leg. * **Safe Injection Site:** To avoid injuring the sciatic nerve (inferior to piriformis) and the superior gluteal nerve, intramuscular injections in the gluteal region are administered in the **upper outer quadrant**. * **Structures passing ABOVE Piriformis:** Only two structures—the Superior Gluteal Nerve and Superior Gluteal Vessels. All other major nerves (Sciatic, Pudendal, Inferior Gluteal) pass **below** it.

Question 346: Which of the following is attached to the head of the fibula?

A. Lateral meniscus
B. Popliteus tendon
C. Fibular collateral ligament (Correct Answer)
D. Posterior cruciate ligament

Explanation: The **head of the fibula** serves as a vital anchoring point for structures on the posterolateral aspect of the knee. ### **Why Option C is Correct** The **Fibular Collateral Ligament (FCL)**, also known as the Lateral Collateral Ligament (LCL), is a cord-like structure that extends from the lateral epicondyle of the femur to the **lateral surface of the head of the fibula**. It is primarily responsible for resisting varus stress. At its insertion, it is split by the tendon of the **biceps femoris**, which also attaches to the fibular head. ### **Why Other Options are Incorrect** * **A. Lateral Meniscus:** Unlike the medial meniscus (which is attached to the tibial collateral ligament), the lateral meniscus is **not** attached to the fibular collateral ligament or the fibula. This makes it more mobile and less prone to injury. * **B. Popliteus Tendon:** The popliteus muscle originates from the lateral condyle of the femur and inserts into the posterior surface of the tibia (above the soleal line). It passes deep to the FCL but does not attach to the fibula. * **D. Posterior Cruciate Ligament (PCL):** The PCL attaches to the posterior intercondylar area of the **tibia** and the medial condyle of the femur. It has no anatomical relationship with the fibula. ### **High-Yield Clinical Pearls for NEET-PG** * **Common Peroneal Nerve:** This nerve winds around the **neck of the fibula**. Fractures at this site can lead to **foot drop** due to paralysis of the anterior and lateral compartment muscles of the leg. * **Biceps Femoris:** This is the only hamstring muscle that attaches to the fibula (head), making it a key landmark during lateral surgical approaches to the knee. * **Stability:** The fibula does not participate in the knee joint proper (it does not articulate with the femur), but it is essential for the stability of the **proximal tibiofibular joint**.

Question 347: What is the most important perforator of the lower limb?

A. Long saphenous vein and posterior tibial vein
B. Short saphenous vein and posterior tibial vein
C. Short saphenous vein and popliteal vein
D. Long saphenous vein and femoral vein (Correct Answer)

Explanation: ### Explanation The correct answer is **D: Long saphenous vein and femoral vein**. **1. Underlying Medical Concept** Perforating veins are vessels that connect the superficial venous system to the deep venous system by "perforating" the deep fascia [1]. The most clinically significant and anatomically "important" perforator is the **Saphenofemoral Junction (SFJ)**. This is the point where the Long Saphenous Vein (Great Saphenous Vein) drains into the Femoral Vein at the fossa ovalis [1]. It is considered the most important because it is the primary site of valvular incompetence leading to primary varicose veins and is the target of surgical interventions like Trendelenburg ligation. **2. Analysis of Incorrect Options** * **Options A & B:** While the **Posterior Tibial Vein** connects to the superficial system via the **Cockett perforators** (lower leg), these are multiple smaller vessels rather than a single primary junction. * **Options B & C:** The **Short Saphenous Vein** drains into the **Popliteal Vein** at the Saphenopopliteal Junction (SPJ). While important, it is anatomically secondary to the SFJ in terms of the volume of blood carried and the frequency of clinical pathology [1]. **3. NEET-PG High-Yield Clinical Pearls** * **Direction of Flow:** In health, blood flows from superficial to deep veins. Incompetent valves in perforators cause "reflux," leading to varicosities and skin changes (lipodermatosclerosis) [2]. * **Named Perforators to Remember:** * **Hunterian (Mid-thigh):** Connects GSV to Femoral vein. * **Dodd’s (Lower thigh):** Connects GSV to Femoral vein. * **Boyd’s (Below knee):** Connects GSV to Gastocnemius/PTV. * **Cockett’s (Ankle):** Connects the posterior arch vein to PTV; these are the most common sites for venous ulcers [3]. * **Trendelenburg Test:** Used clinically to differentiate between SFJ incompetence and perforator incompetence.

Question 348: Which of the following statements is true about the ankle joint?

A. The joint is strengthened by the deltoid ligament.
B. It is more stable in a dorsi-flexed position.
C. It is a hinge joint.
D. All of the above. (Correct Answer)

Explanation: The ankle joint (talocrural joint) is a classic high-yield topic in NEET-PG Anatomy. Here is the breakdown of why all the provided statements are correct: **1. Strengthening by the Deltoid Ligament (Option A):** The medial aspect of the ankle is reinforced by the powerful, fan-shaped **deltoid ligament**. It is significantly stronger than the lateral ligaments, which is why eversion sprains are rare compared to inversion sprains. It connects the medial malleolus to the talus, calcaneus, and navicular bones. **2. Stability in Dorsiflexion (Option B):** The superior surface of the talus (trochlea) is **wider anteriorly** than posteriorly. During dorsiflexion, the wider anterior part of the talus wedges tightly between the medial and lateral malleoli, locking the joint and making it most stable. Conversely, in plantarflexion, the narrower posterior part of the talus resides in the mortise, making the joint relatively unstable and prone to injury. **3. Classification as a Hinge Joint (Option C):** The ankle is a **synovial hinge joint** (ginglymus). It primarily allows movement in one plane: dorsiflexion and plantarflexion. Inversion and eversion occur at the subtalar and midtarsal joints, not the ankle joint itself. **Clinical Pearls for NEET-PG:** * **Most common ligament injured:** The **Anterior Talofibular Ligament (ATFL)** during an inversion stress (sprain). * **Pott’s Fracture:** A bimalleolar fracture occurring due to forced eversion, often involving a tear of the deltoid ligament or avulsion of the medial malleolus. * **Nerve Supply:** Deep peroneal and tibial nerves (Hilton’s Law).

Question 349: All of the following muscles attach to the lesser trochanter of the femur, EXCEPT?

A. Psoas major
B. Psoas minor (Correct Answer)
C. Adductor magnus
D. Iliacus

Explanation: The **lesser trochanter** is a small, conical projection located on the posteromedial aspect of the proximal femur. It serves as the primary insertion site for the powerful hip flexors. ### **Why Psoas Minor is the Correct Answer** The **Psoas minor** is a weak flexor of the trunk that is absent in approximately 40-50% of the population. Unlike the psoas major, it does not reach the femur. Instead, it inserts into the **pectineal line of the pubis** and the **iliopubic eminence**. Therefore, it has no attachment to the lesser trochanter. ### **Analysis of Incorrect Options** * **Psoas Major (A) & Iliacus (D):** These two muscles merge to form the **Iliopsoas tendon**, which is the principal muscle of hip flexion. The Iliopsoas inserts directly onto the **apex and anterior surface of the lesser trochanter**. * **Adductor Magnus (C):** While the bulk of the adductor magnus inserts into the linea aspera and adductor tubercle, its **superior-most fibers** (sometimes called the *adductor minimus*) insert into the area extending from the **quadrate tubercle down to the posterior surface of the lesser trochanter**. ### **NEET-PG High-Yield Pearls** * **Iliopsoas:** The strongest flexor of the hip. In cases of **Iliopsoas Abscess** (often secondary to TB of the spine), the pus tracks down the psoas sheath and may point just below the inguinal ligament. * **Lesser Trochanter Fractures:** In adults, an isolated avulsion fracture of the lesser trochanter is rare and is considered a **pathognomonic sign of metastatic malignant infiltration** until proven otherwise. * **Nerve Supply:** Iliacus (Femoral nerve L2-L3); Psoas major (Ventral rami of L1-L3).

Question 350: At what gestational age does the center of ossification of the femur appear?

A. 36 weeks (Correct Answer)
B. 38 weeks
C. 40 weeks
D. 28 weeks

Explanation: The correct answer is **36 weeks**. ### **Educational Explanation** **1. Why 36 weeks is correct:** The **distal femoral epiphysis** is the first secondary center of ossification to appear in the human body. It typically appears between **35 to 36 weeks** of intrauterine life. In the context of forensic medicine and neonatology, its presence is a critical medicolegal marker indicating that the fetus is **full-term** (or near-term) and viable. If a newborn's X-ray shows this ossification center, it confirms a gestational age of at least 36 weeks. **2. Analysis of Incorrect Options:** * **28 weeks (Option D):** At this stage, only primary centers of ossification (diaphyses) of long bones are present. Secondary centers have not yet appeared. * **38 weeks (Option B) & 40 weeks (Option C):** While the distal femoral center is certainly present at these ages, it *first* appears at 36 weeks. By 38–40 weeks, the **proximal tibial epiphysis** usually begins to appear (typically at 38 weeks or birth). ### **High-Yield Clinical Pearls for NEET-PG** * **Order of Appearance:** Distal Femur (36 weeks) → Proximal Tibia (38 weeks/Birth) → Cuboid (Birth/40 weeks). * **Casper’s Dictum:** This refers to the use of these ossification centers to determine the age of a fetus during an autopsy. * **Rule of Halves:** The femur is a common site for measuring "Limb Length" in obstetric ultrasounds to estimate gestational age in the second trimester. * **Clinical Significance:** The distal femoral epiphysis is the "growing end" of the femur; any injury here (like a Salter-Harris fracture) can lead to significant limb length discrepancy.

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Arterial Supply and Venous Drainage

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Muscles and Their Actions

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Lower Limb — MCQs

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